1. Field of the Invention
The present invention relates to a developing device included in a copier, facsimile apparatus, printer or similar image forming apparatus and, more particularly, to a developer replenishing device for replenishing the developing device with a developer, and a developer container for use therewith.
2. Discussion of Background
Copiers, facsimile apparatus, printers or similar electrophotographic image forming apparatus, which electrostatically form a latent image on a photoconductive element, develop the latent image with charged color particles, i.e., a developer, and then transfers the developed image to a paper, are well known. It is a common practice with this type of apparatus to supplement a fresh developer when a developer stored in a vessel is consumed. A device for replenishing the developer may be implemented with a hollow cylindrical container storing the developer, as taught in, for example, Japanese Patent Laid-Open Publication (Kokai) Nos. 59-188678 and 60-146265. The container is substantially entirely open at a first end thereof to form a developer outlet and is rotated about the longitudinal axis thereof to sequentially discharge the developer, or powder, to the vessel of the image forming apparatus via the outlet. To replace the container with a new container filled with a fresh developer, a holder, which is positioned horizontally on the body of the image forming apparatus, is rotated downwardly to a vertical position around the first end thereof. In this condition, the empty container is removed from the holder, and then a new container is mounted on the holder. Subsequently, the holder is again rotated to the horizontal position where the new container can replenish the apparatus with the developer. Before the new container is put on the holder, which is maintained in the vertical position, the container is positioned such that the opening, or developer outlet, thereof faces upwardly, and then a cap, which closes the opening, is removed. The container, without the cap, is mounted on the holder with the opening facing upwardly, so that the powder filling the container will not fall out.
However, a prerequisite with the conventional scheme described above is that the length of the holder should not be greater than the height of the apparatus, because the holder has to rotated between the horizontal position and the vertical position around the first end thereof. Generally, the apparatus is provided with as small a height as possible to meet the demand for a miniature configuration, requiring the holder and, therefore, the container, to be as short as possible. As a result, the quantity of developer available within a single container is reduced, resulting in the frequent replacement of the container. In any case, the conventional replenishing device cannot be reduced in size and suffers from design limitations in relation to the internal arrangement of an image forming apparatus.
In light of the above, a series of studies and experiments were conducted in order to implement an arrangement for allowing a person to replace the cylindrical container, while maintaining the holder in the horizontal position. However, since the container is substantially fully open at the first end thereof, the developer stored therein falls through the outlet of the container, when the container is mounted on the holder. Therefore, in Japanese Patent Laid-Open Publication No. 3-2881, a developer replenishing device is proposed which uses a container closed at both ends thereof and which is formed with a developer outlet in the circumferential wall thereof adjacent to one of the closed ends. This kind of container is placed on a holder with the outlet facing upwardly. However, considering the fact that an image forming apparatus is most often used by ordinary clerks, it is likely that the container may be inadvertently mounted on the holder with the outlet facing downwardly. In this case, the developer may fall out of the container and smear the apparatus and the floor. In addition, a dead space is produced between the outlet and the adjoining end of the container, requiring the container to be provided with an additional length matching the dead space.